[Fedora-xen] Re: What are the minimal required FC6 packages for Dom0?
Hi,
Actually, just a small point of clarification. Guest OSes can know if
they're running in a hypervisor in hardware virtualization. If you're
using AMD-V, there's an instruction called VMMCALL that allows the
guest OS to check to see if it's running under a hypervisor or not.
On Intel, the equivalent instruction is VMCALL. This is useful
because if it finds that it is running under a hypervisor, it can do
things such as ask for more memory if it's running out of memory or
ask for more disk space. Here's an article about if:
http://developer.amd.com/articles.aspx?id=15&num=3 You can also
search google for VMMCALL or VMCALL :)
PS. Of course, the guest OS would have to have the ability to do this
check. I'm not sure how complicated it would be. Probably a patch to
the kernel or something.
On Sat, Oct 07, 2006 at 11:12:00PM +0200, Aryanto Rachmad wrote:
> ----- Original Message -----
> From: "Daniel P. Berrange" <berrange redhat com>
> To: "Aryanto Rachmad" <aryanto chello at>
> Cc: <fedora-xen redhat com>
> Sent: Saturday, October 07, 2006 10:43 PM
> Subject: Re: [Fedora-xen] What are the minimal required FC6 packages for Dom0?
>
>
> >
> > Fully-virt just lets you run unmodified operating systems (notably Windows,
> > or older versions of Linux for which there is no Xen kernel available).
> > If you only care about running modern Xen enabled Linux kernels then
> > you have on need for fully-virt. As a general rule, if there is a paravirt
> > version of your desired OS available, using that will always be preferrable
> > to fullyvirt. The network & disk I/O is much faster in paravirt, and since
> > the kernel is informed when the hypervisor re-schedules it, it can do much
> > more accurate process accounting in the guest. It is basically impossible
> > to do accurate process scheduling in fully-virt, since the guest kernel
> > has no knowledge of the fact that its running under a hypervisor.
> >
>
> Thanks a lot Dan,
>
> I am actually planning to use Windows XP on one of the guests. So in this case I can
not
> do that, cann't I? But on the other hand, I prefer para-virtualised as it has
more
> advantages as you explained.
Yeah, for Windows XP you'll need an Intel-VT or AMD-V capable CPU.
Regards,
Dan.
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